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package org.openjdk.jmh.samples;


import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.Fork;

import org.openjdk.jmh.annotations.Measurement;

import org.openjdk.jmh.annotations.OutputTimeUnit;

import org.openjdk.jmh.annotations.Scope;

import org.openjdk.jmh.annotations.State;

import org.openjdk.jmh.annotations.Warmup;

import org.openjdk.jmh.runner.Runner;

import org.openjdk.jmh.runner.RunnerException;

import org.openjdk.jmh.runner.options.Options;

import org.openjdk.jmh.runner.options.OptionsBuilder;


import java.util.concurrent.TimeUnit;


@State(Scope.Thread)

@OutputTimeUnit(TimeUnit.MICROSECONDS)

@Fork(1)

public class JMHSample_20_Annotations {


 double x1 = Math.PI;


 /*

  * In addition to all the command line options usable at run time,

  * we have the annotations which can provide the reasonable defaults

  * for the some of the benchmarks. This is very useful when you are

  * dealing with lots of benchmarks, and some of them require

  * special treatment.

  *

  * Annotation can also be placed on class, to have the effect over

  * all the benchmark methods in the same class. The rule is, the

  * annotation in the closest scope takes the precedence: i.e.

  * the method-based annotation overrides class-based annotation,

  * etc.

  */


 @Benchmark

 @Warmup(iterations = 5, time = 100, timeUnit = TimeUnit.MILLISECONDS)

 @Measurement(iterations = 5, time = 100, timeUnit = TimeUnit.MILLISECONDS)

 public double measure() {

  return Math.log(x1);

 }


 /*

  * ============================== HOW TO RUN THIS TEST: ====================================

  *

  * Note JMH honors the default annotation settings. You can always override

  * the defaults via the command line or API.

  *

  * You can run this test:

  *

  * a) Via the command line:

  *    $ mvn clean install

  *    $ java -jar target/benchmarks.jar JMHSample_20

  *

  * b) Via the Java API:

  *    (see the JMH homepage for possible caveats when running from IDE:

  *      http://openjdk.java.net/projects/code-tools/jmh/)

  */


 public static void main(String[] args) throws RunnerException {

  Options opt = new OptionsBuilder()

          .include(JMHSample_20_Annotations.class.getSimpleName())

          .build();


  new Runner(opt).run();

 }
// 本例介绍了所有在main方法中通过Options提供的参数都可以通过注解写在需要测试的方法上，这在编写大量需要不同运行环境的基准测试时显得非常方便，比如这样

}